Downhole coupon holder

Abstract

A first type of coupon holder includes an elongated core that is axially aligned with a coupon holder axis and an external surface that circumscribes the elongated core. The external surface defines coupon mounting surfaces with different radial orientations relative to the coupon holder axis. The coupon mounting surfaces are circumferentially aligned around the elongated core and have geometric centers with the same axial position along the coupon holder axis. A second type of coupon holder includes an elongated support structure that is axially aligned with a coupon holder axis and a coupon holder body positioned to have an end face in a plane transverse to the coupon holder axis. The coupon holder body has a plurality of slots to receive end portions of coupons. The slots are in a circular arrangement around the coupon holder axis and position coupons in parallel to the coupon holder axis.

The invention claimed is: 
     
       1. An apparatus comprising:
 an elongated support structure axially aligned with a coupon holder axis; 
 a coupon holder body positioned to have an end face in a plane transverse to the coupon holder axis, the coupon holder body having a plurality of slots disposed in a circular arrangement around the coupon holder axis, the plurality of slots having open ends on the end face, the plurality of slots to receive end portions of a plurality of coupons through the open ends and position the plurality of coupons in parallel to the coupon holder axis and around the elongated support structure, wherein the coupon holder body comprises a ring body having a central opening, and wherein the plurality of slots is disposed in a circular arrangement around the central opening; and 
 a coupon holder housing having a bore, wherein the coupon holder body is disposed within an annular cavity formed within the bore, and wherein an end portion of the elongated support structure extends through the central opening in the coupon holder body into the bore. 
 
     
     
       2. The apparatus of  claim 1 , wherein the plurality of slots are selected from cylindrical slots to receive end portions of cylindrical rod coupons, flat-sided slots to receive end portions of flat rod coupons, and curved slots to receive end portions of curved coupons. 
     
     
       3. The apparatus of  claim 1 , wherein the plurality of slots have shapes to receive end portions of at least two different types of coupon shapes selected from flat rod coupon shape, cylindrical rod coupon shape, and curved coupon shape. 
     
     
       4. The apparatus of  claim 1 , further comprising an end connection coupled to one end of the coupon holder body and an end fitting coupled to one end of the elongated support structure, the end connection comprising a threaded surface for forming a threaded connection, the end fitting having a bull nose shape. 
     
     
       5. The apparatus of  claim 1 , further comprising a plurality of coupons having end portions mounted in the plurality of slots, the plurality of coupons positioned in parallel to the coupon holder axis and around the elongated support structure by the slots, the plurality of coupons selected from cylindrical rod coupons, flat rod coupons, and curved coupons.